Small TAF question

LongRoadBob

LongRoadBob

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Oslo, Norway
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Jacker
Given this TAF:
TAF 310500Z 3106/0106 04008KT 9000 -SN SCT005 BKN020 TEMPO
3106/0106 BKN005


I'm a little unsure about the TEMPO. My undestanding was that TEMPO was the forecast within the next 60 minutes which might differ from the main TAF.
But this is followed by a "from/until" date-time, which also corresponds exactly with the main TAF.
(0600UTC today until 0600UTC tomorrow).

SO is the cloud ceiling expected to be at 2000' or 500'?

Another question not with this TAF, but in TAF or METAR during very overcast conditions, at home I am near a valley and can see that it visibility is low, sometimes very low but the TAF may give visibility as 9999 BUT with a VV008 for example. I can see it is hazy, and I have been assuming jus that there is a VV entry it indicates that visibility is not good enough for VFR, but I really don't know.

Also, anyone have any links to web pages that go into reading TAF/METAR and interpreting? NOT decoding, but I'm looking for how to interpret the decoded as far as what it really means for VFR flying. I found only one site so far which was good and also mentioned that the presence of VV in a report was a warning sign. It also mentioned that if one subtracts wind from gust, that numbe could be an indicator of wind shear.
They gave an example where say wind was 7knots G14 and so 7 is the diff, and that was something to consider but if it were say 10 or above it would be cause for worry.

Things like that. Looking for ways to think about "putting it all together".
 
It means that during the entire time of the forecast there will be times for less than 1 hour that the ceiling can/may/will drop to 500. So for maybe 15 minutes a low layer of clouds will move through the area dropping the ceiling to 500'. Then for 2 hours it will be 2000' ceiling, then for 20 minutes, back down to 500'. Then for 45 minutes back to 2000, and so on.

Here's a TAF from this morning

MC CLELLAN-PALOMAR | CARLSBAD, CA
KCRQ 311053Z AUTO 00000KT 8SM CLR 13/11 A2995 RMK AO2 SLP139 T01330106
KCRQ 311004Z 3110/0106 VRB04KT P6SM SCT015 BKN200
TEMPO 3111/3115 OVC015
FM311700 20012KT P6SM BKN022
FM312100 20012KT 3SM RA OVC018
FM010300 VRB05KT P6SM VCSH BKN020

From 11z to 15z on the 31st, there will be sporadic instances of the ceiling dropping from BKN2000 to OVC015. For most of that time period it will be BKN200, but there will be occasions where it drops to 015.

For the TEMPO to be issued, it means that those conditions, in this case OVC015, will last less than 1 hour at a time. If they lasted more than 1 hour, it would get it's own FM31xxxx forecast block.

Make sense?
 
Last edited:
EdFred said:
It means that during the entire time of the forecast there will be times for less than 1 hour that the ceiling can/may/will drop to 500. So for maybe 15 minutes a low layer of clouds will move through the area dropping the ceiling to 500'. Then for 2 hours it will be 2000' ceiling, then for 20 minutes, back down to 500'. Then for 45 minutes back to 2000, and so on.

Here's a TAF from this morning

MC CLELLAN-PALOMAR | CARLSBAD, CA
KCRQ 311053Z AUTO 00000KT 8SM CLR 13/11 A2995 RMK AO2 SLP139 T01330106
KCRQ 311004Z 3110/0106 VRB04KT P6SM SCT015 BKN200
TEMPO 3111/3115 OVC015
FM311700 20012KT P6SM BKN022
FM312100 20012KT 3SM RA OVC018
FM010300 VRB05KT P6SM VCSH BKN020

From 11z to 15z on the 31st, there will be sporadic instances of the ceiling dropping from BKN2000 to OVC015. For most of that time period it will be BKN200, but there will be occasions where it drops to 015.

For the TEMPO to be issued, it means that those conditions, in this case OVC015, will last less than 1 hour at a time. If they lasted more than 1 hour, it would get it's own FM31xxxx forecast block.

Make sense?
Click to expand...

Makes perfect sense! Thanks.
That helped a lot!
 
PaulMKE said:
Please review AIM 7-1-29.
Click to expand...

It maybe because I’m looking at a 2016 AIM, but that’s “Thunderstorm Flying”? Nevertheless, it’s close enough - Fig 7-1-22 & -23 plus section 7-1-31 in mine are where it’s all at.
 
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